用对象数组实现一个简单的银行账户管理系统，完成多个用户的开户、存款、取款和查询余额等行为。

在使用对象数组实现一个简单的银行账户管理系统时，我们可以创建一个`BankAccount`类，它包含属性如账号、姓名和余额，以及对应的操作方法如`openAccount()`、`deposit()`, `withdraw()` 和 `checkBalance()`。以下是基本的步骤：

1. 首先，定义`BankAccount`类：

public class BankAccount {
    private String accountNumber;
    private String name;
    private double balance;

    public BankAccount(String accountNumber, String name) {
        this.accountNumber = accountNumber;
        this.name = name;
        this.balance = 0;
    }

    // 开户方法
    public void openAccount() {
        System.out.println(name + "的账户已开设，账号：" + accountNumber);
    }

    // 存款方法
    public void deposit(double amount) {
        if (amount > 0) {
            balance += amount;
            System.out.println(name + "存入了" + amount + "元，当前余额：" + balance);
        } else {
            System.out.println("无效的存款金额");
        }
    }

    // 取款方法
    public boolean withdraw(double amount) {
        if (amount <= balance) {
            balance -= amount;
            System.out.println(name + "取出了" + amount + "元，当前余额：" + balance);
            return true;
        } else {
            System.out.println("取款金额超过余额");
            return false;
        }
    }

    // 查询余额方法
    public double checkBalance() {
        return balance;
    }
}

2. 创建一个`BankManager`类，用于管理用户数组：

import java.util.ArrayList;

public class BankManager {
    private ArrayList<BankAccount> accounts;

    public BankManager() {
        accounts = new ArrayList<>();
    }

    // 添加用户账户
    public void addUser(BankAccount account) {
        accounts.add(account);
    }

    // 管理操作
    public void manageAccounts(String action, String[] args) {
        for (BankAccount account : accounts) {
            switch (action) {
                case "开户":
                    account.openAccount();
                    break;
                case "存款":
                    account.deposit(Double.parseDouble(args[0]));
                    break;
                case "取款":
                    account.withdraw(Double.parseDouble(args[0]));
                    break;
                case "查询":
                    System.out.println(account.getName() + "'s Balance: " + account.checkBalance());
                    break;
                default:
                    System.out.println("未知操作");
            }
        }
    }
}

现在你可以创建`BankManager`实例，添加用户并进行各种操作：

public static void main(String[] args) {
    BankManager bank = new BankManager();
    bank.addUser(new BankAccount("123456", "张三"));
    bank.addUser(new BankAccount("789012", "李四"));

    bank.manageAccounts("开户", new String[]{""});
    bank.manageAccounts("存款", new String[]{"5000"});
    bank.manageAccounts("取款", new String[]{"2000"});
    bank.manageAccounts("查询", new String[]{});
}